We will improve the radio component of an inexpensive, miniature battery-operated digital telemetric system (DT) for new applications in neuroscience. DT exploits commercially available digital audio integrated circuits and protocols to record, digitize, and transmit bioelectric signals without wires. Phase 1 is based on a prototype designed to record the activity of ensembles of single neurons from the brains of freely-moving rats. The DT version 4 (DT4) prototype has 16 inputs, is 10g and operates >4h from an 18g battery. DT4 digitizes signals at 24-bit resolution, allowing signals as small as 10 uVto be resolved. Each input is lowpass filtered (6 kHz) and digitized (12 kHz). The digital signals are combined into a single data stream and the serialized data are then transmitted to a remote DSP-based recording system via either an optical fiber or a 2.4 GHz radio channel. Measurements by DT4 surpass current standards, but the current radio transmission is unreliable when radio frequency interference (RFI) is high due to multi-path reflections and Wi-Fi and Bluetooth devices. Specific aim 1 is to use RRM techniques in the DT for reliable radio transmission. Deliverable 1 is a 2-ch wireless module. Deliverable 2 is a 16-ch wireless system based on eight 2-ch modules. Deliverable 3 is to characterize and test deliverable 2 by recording ensembles of neurons in freely-moving rats. For non-interactive applications, wireless recording is not advantageous if the recording device itself (usually a PC) is not also portable. Specific aim 2 is to build a prototype DT with wireless USB for animal research. A tethered USB version of the DT will be developed for Deliverable 4. Once a wireless USB controller is available, replacing the "wired" USB chipset by its wireless equivalent should be relatively straightforward; if the latter is available, Deliverable 5 will be a prototype DT based on the wireless USB standard. In Phase II, to commercialize the device for neuroscience research we will reduce the device's size and cost and make first steps towards realizing a DT for clinical use.